ICES advice 2018

ICES advice on fishing opportunities

ICES advises that when the MSY approach is applied, and assuming that discard rates and fishery selection patterns do not change from the average of 2015–2017, catches in 2019 should be no more than 3270 tonnes.

To ensure that the stock in Functional Unit 11 is exploited sustainably, management should be implemented at the functional unit level.

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Stock development over time

The historical harvest rate has fluctuated around FMSY and has been below FMSY since 2013. The stock has been above MSY Btrigger since 1998.

Figure 1 Summary of the stock assessment of Norway lobster in Division 6.a, Functional Unit 11. Catches (discard data only available from 1990), harvest rate (sum of landings and dead discards in numbers, divided by total abundance), survey abundance (Underwater TV, millions; SSB proxy; approximate 95% confidence intervals). Harvest rates before 2006 may be unreliable due to underreporting of landings. Orange lines represent MSY Btrigger and the FMSY harvest rate proxy.

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Stock and explotation status

ICES assesses that fishing pressure on the stock is below FMSY, while spawning stock size is above MSY Btrigger.

Table 1 State of the stock and fishery relative to reference points for Norway lobster in Division 6.a, Functional Unit 11.

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Catch scenarios

Table 2 The basis for the catch scenarios. Norway lobster in Division 6.a, Functional Unit 11.

Variable	Value	Notes
Stock abundance (2019)	1215 million	UWTV Survey 2018 (number of individuals)
Mean weight in wanted catch	25.83 g	Average 1999–2017
Mean weight in unwanted catch	10.97 g	Average 1999–2017
Unwanted catch	10.6%	Average 2015–2017 (proportion by number)
Discards survival	25%	Proportion by number
Dead unwanted catch	8.2%	Average 2015–2017 ( proportion by number)

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Table 3 Annual catch advice and scenarios for Norway lobster in Division 6.a, Functional Unit 11; discarding is assumed to continue at the recent average. All weights are in tonnes.
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The change in advice is a result of the inclusion of the 2018 survey and updating mean weights and discard rates.

Basis of the advice

Table 4 The basis of the advice for Norway lobster in Division 6.a, Functional Unit 11.

Advice basis	MSY approach.
Management plan	The EU has proposed a multiannual management plan for the Western Waters, which is not yet finalized (EU, 2018).

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Quality of the assessment

Since 1994 the underwater TV survey (UWTV) has provided abundance estimates by functional unit (FU) with acceptable precision. The UWTV survey for FU 11 does not cover Nephrops grounds in the inshore waters and sea lochs, waters that are typically fished by smaller vessels. The total area of these grounds is estimated to be less than 5% of the total stock areas and therefore the exclusion of these inshore areas from the survey is not considered to impact the quality of the assessment.

In 2017, observer sampling from the Scottish Industry–Science observer sampling scheme was extended to include sampling of Norway lobster catches in FU 11. As a result the sampling levels have increased and discard proportions are more precisely estimated.

Biological sampling for this stock is considered sufficient.

The long-term average (rather than a three-year average) was considered more appropriate as input for the mean weight in landings and discards in the calculation of catch scenarios. This is due to interannual variation.

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Issues relevant for the advice

From 2016, the EU landing obligation was applied to all catches of Norway lobster fisheries in ICES Subarea 6, with several exemptions. Observations from the 2016–2017 fishery indicate that some discarding above the minimum conservation reference size (MCRS) continues and has not changed markedly (Figure 3). Consequently, ICES is providing advice for 2019 assuming average discard rates as observed over the last three years, which is considered to be a more realistic assumption.

For FU 11, the absolute density observed in the UWTV survey is intermediate compared to other Nephrops FUs, with an average density of around 0.6 individuals m−2. This suggests the stock may have a medium productivity capability. Historical harvest ratios in this FU have been around F35%SPR and landings have been relatively stable in the last thirty years. For these reasons, F35%SPR (combined between sexes) is considered to deliver high long-term yield with a low probability of recruitment overfishing and is therefore chosen as a proxy for FMSY.

A single TAC covers the entire ICES Subarea 6. Management should be implemented at the functional unit level to ensure that fishing opportunities are in line with the scale of the resource for each of the stocks and the corresponding MSY approach.

Figure 2 Norway lobster functional units in subareas 6 and 7.

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Reference Points

Table 5 Reference points, values, and their technical basis. Norway lobster in Division 6.a, Functional Unit 11.
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Basis of the assessment

Table 6 Basis of the assessment and advice for Norway lobster in Division 6.a, Functional Unit 11.

ICES stock data category	1 (ICES, 2018a).
Assessment type	Underwater TV survey.
Input data	One survey index (UWTV-FU11); commercial catches (international landings, length frequencies from Scottish catch sampling); fixed maturity parameters from survey data; fixed natural mortalities. Discard survival rate.
Discards and bycatch	Included in the assessment since 1990, data series from the majority of the main fleets covering all landings.
Indicators	Size structure, mean size, and sex ratio of catches.
Other information	The latest benchmark (based on the UWTV survey) was performed in 2013 (ICES, 2013).
Working group	Working Group for the Celtic Seas Ecoregion (WGCSE)

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Information from stakeholders

No additional information is available for this stock.

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History of the advice, catch, and management

Table 7 . ICES advice, landings and discards of Norway lobster in Division 6.a, Functional Unit 11. All weights are in tonnes.
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History of the catch and landings

Table 8 Catch distribution by fleet in 2017 as estimated by ICES for Norway lobster in Division 6.a, Functional Unit 11.

Catch	Landings	Total.discards
	Directed Nephrops fishery | Mixed Nephrops/demersal fishery
99.4% dead | 0.6% surviving	83.4% trawl 14.8% creels | 1.8% trawl	75% dead | 25% surviving
2512 t	2448 t	64 t

Table 9 History of ICES estimates of landings (for Scotland by gear) and total discards of Norway lobster in Division 6.a, Functional Unit 11. All weights are in tonnes.
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Sources and references

• EU. 2018. Proposal for a REGULATION OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL establishing a multiannual plan for fish stocks in the Western Waters and adjacent waters, and for fisheries exploiting those stocks, amending Regulation (EU) 2016/1139 establishing a multiannual plan for the Baltic Sea, and repealing Regulations (EC) No 811/2004, (EC) No 2166/2005, (EC) No 388/2006, (EC) 509/2007 and (EC) 1300/2008. COM/2018/0149 final. 30 pp. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:52018PC0149&from=EN.
• ICES. 2013. Report of the Benchmark Workshop on Nephrops (WKNEPH), 25 February–1 March 2013, Lysekil, Sweden. ICES CM 2013/ACOM:45. 230 pp.
• ICES. 2016. EU request to ICES to provide FMSY ranges for selected stocks in ICES subareas 5 to 10. In Report of the ICES Advisory Committee, 2016. ICES Advice 2016, Book 5, Section 5.4.1. 13 pp.
• ICES. 2018a. Advice basis. In Report of the ICES Advisory Committee, 2018. ICES Advice 2018, Book 1, Section 1.2. https://doi.org/10.17895/ices.pub.4503.
• ICES. 2018b. Report of the Working Group for the Celtic Seas Ecoregion (WGCSE), 9–18 May 2018, ICES Headquarters, Copenhagen, Denmark. ICES CM 2018/ACOM:13. 1340 pp.